Multi-stage turbo-compressors



Aug. 25, 1964 H. DOLZ 3,145,913

MULTI-STAGE TURBO-COMPRESSORS Filed Oct. 30, 1962 i 2 Sheets-Sheet 1 III INVENI'OE flew/k6 20% Aug. 25, 1964 H. 061.2

MULTI-STAGE TURBO-COMPRESSORS 2 Sheets-Sheet 2 Filed Oct. 50, 1962 INVENTQR. O o I azzz'zck Doz United States Patent Claims priority, application Germany Nov. 3, 1961 9 Claims. (Cl. 230-130) This invention relates to turbo-compressors, and more particularly to a turbo-compressor capable of delivering small amounts of gas at high pressure.

In turbo-compressors of known construction the lower limit of the economical delivery capacity is fixed by the gap between the rotor and the stationary casing, or between the rotor and a stationary guide wheel, because part of the gas delivered towards the pressure side of the rotor flows back to the suction side through this gap. The sealing of the rotors by means of labyrinth shaft packings, and also by means of cover sheets, does indeed diminish these clearance losses, but they do not admit of being fundamentally avoided.

The present invention relates to a turbo-compressor which does not exhibit the clearance losses just described, because the said gaps between rotor and casing or between rotor and guide wheel are not present at all. According to this invention the rotors are connected fixedly and in a gastight manner with the outer casing, which accordingly revolves along with the rotors, whilst the guide wheels of the individual stages are journalled in a readily rotatable manner in the interior of the casing rotating therewith, between the individual rotors, and are prevented from rotating therewith by gravity, for instance by means of eccentric weights fastened to them, that is to say, they are stationary in accordance with their function. Such a compressor needs gastight sealing only at the outlet from the last stage and at the in let to the first stage, and in air-compressors even the latter may be omitted. It is not necessary to seal the individual stages from one another. This is a further advantage over turbo-compressors of known construction.

The freely journalled guide wheels may alternatively be fettered or held stationary by external stationary magnetic fields. This has the further advantage, as compared with fettering by gravity, of independence of position of the turbo-compressor.

The fettering of the freely journalled and readily ro-' tatable guide wheels by external field forces, such as gravity or magnetic force, is an essential feature of the invention.

Since aharmful reflux, through gaps, of the gas delivered, is not possible, because there are no' such gaps, there is also no lower limit to the delivery capacity. The usual distribution of the rotor blades over the entire periphery of the rotor leads, however, in the case of continually decreasing delivery outputs, to rotor ducts which become progressively lower in axial extent. This would be a disadvantage, on account of the losses connected therewith through gaseous friction on the walls of the rotor ducts, above all in rotors of large diameter.

This disadvantage is obviated in a further development of the invention by the fact that only a portion of the periphery of the rotors is set with blades, with only two blades, in the simplest case, which are located diametrically opposite to one another.

3,145,913 Patented Aug. 2 5, 1964 This only partial equipment of the periphery of the r05 tors with blades renders it possible to employ rotors of the same diar'neterin all the stages of such a compres sor. In correspondence with the differing volumetric capacities of the individual stages, the associated rotors are equipped with the appropriatenumbers of rotor blades.- Alternatively rotors with equal numbers of blades may be provided, in which case, in the stages of smaller volii metric capacity, only the corresponding number of rotor blades are left open, the remainder being closed in a gastight manner, for instance by means of suitable in sertions. Finally, the rotor blades may even be varied in their peripheral extent and in their axial height. I

The use of rotors of the same diameter yields equal external dimensions of the individual compressor stages; This enables a system of assembling pre-fabricated machine parts to be carried out in the most economical manner. According to the particular pressure ratio deQ sired, the appropriate number of compressor stages is as sembled, which differ from one another onlyin the arrangement of the rotor blades in the rotors; The silbse quent addition of a further stage to an existing compres sor according to the invention can be contemplated.

A three-stage radial-flow compressor for the delivery of air is illustrated by way of example in the accompanying drawings, in which:

FIGURE 1 shows the compressor in axial section;

FIGURE 2 shows a section of the rotor of the first stage on the line IIII of FIGURE 1;

FIGURE 3 shows a section, on the line III-III in FIGURE 1, of the chamber of the guide wheel of the first stage, with the eccentric weights arranged therein for fettering the guide wheel bythe force of gravity; and

FIGURE 4 shows the compressor of FIGURE 1 enclosed in a gastight housing. I

The revolving compressor casing, whith rotors fixedly mounted therein, is rotatably journalled both at the gasinlet end and at the gas-outlet end. In the left-hand cov er 1 of the compressor casing a drive shaft 2 is inserted fixedly and secured against relative rotation. This shaft is supported by the ball bearing 3 on a bearing block 4. The right-hand cover 5 of the compressor casing is' con-i structed for the direct accommodation of a ball bearing 6 on a bearing block 7. The bearing blocks 4 and 7 are bolted to mounting stands 8 and 9, which restupon a common mounting frame 10, and are connected fast'with' the latter.

In the first stage of the compressor, the radial-flow wheel 11 and the part 12 of the casing form a positive or form-closedv unit, which on manufacturing ground is preferably built up from two parts, which are held to gether in a gastight manner by riveting, bolting, cementing or otherwise. The gap between the rotor and the.

casing, which is unavoidable in turbo-compressors fof known construction, is no longer present, and the cavity of the casing is axially divided into two portions by the rotor. The rotorll is not equipped with blades over the entire periphery, as has hitherto been usual and even necessary, but only two diametrically opposite rotor ducts 13 are provided, as will be seen from FIGURE 2. Each duct 13 has two radially spaced orifices which communicate with respective portions of the cavity in the cats 1 3 a return flow of the gas delivered through gaps cannot in any case occur.

The guide wheel consists of a guide-wheel body 14, with blades secured thereto for the radially inward deflecting and returning of the air delivered from the radially outer orifice of the ducts 13, and a guide-wheel cover 16, which closes a chamber 17 in the guide-wheel body 14. On account of the delivery being kept low, and of the air issuing only from two opposite rotor ducts and not throughout the entire rotor periphery, the actual guide blades have been omitted, so that here the work is being done with a bladeless annular chamber, which is appended to the gas-outlet end of the rotor. It is obviously possible, in case of need, to provide guide blades in the annular chamber, which would be secured to the guide wheel, that is, in the present case, to the guidewheel cover 16.

The shaft 18 of the guide-wheel body 14 is supported by means of ball bearings in the rotors 11 and 21 lo cated one on each side of this guide wheel. In this way the easy and free rotatability of the guide wheel, required according to the teaching of this invention, is ensured.

A torque, though but a small torque, is exerted upon the freely rotatable guide wheels 14, 15, 16 by the air delivered by the rotor and flowing out from the rotor ducts 13, and by air friction, journal friction and various other influences. The guide wheel tends to participate in this rotation. In order to prevent this, and to constrain the guide wheel to remain stationary in accordance with its function, an opposing torque must come into operation, to fetter the guide wheel. Weights 20, freely movable upon guiding rods 19 in the chamber 17 of the guidewheel body 14, provide for this counter-torque, because they locate the centre of gravity of the guide wheel in a region below the shaft 18.

The two weights 20 will always assume the position represented in FIGURE 3. One of the weights 20 will always bear on the outer periphery of the chamber 17, and the other on the inner periphery of the chamber 17. Now when the compressor is in operation, the guide wheel is turned out of the position shown in FIGURE 3, with the weights 20 located perpendicularly one above the other, until the counter-torque produced by the weights 20, owing to the action of the force of gravity, has become equal to the external torque with which the air delivered, air friction, journal friction and so forth are acting on the guide wheel. Hence, according to the magnitude of the weights 20 and the magnitude of the external torque acting on the guide wheel, a stable angular position of the guide wheel adjusts itself, at which the guide wheel reaches the requisite stationary position and is fettered. By appropriate dimensioning of the weights 20 the result can always be obtained that the opposing torque of the Weights 20 always remains greater than the external torque acting on the guide wheel. Finally, care should be taken that the external torque acting on the guide wheel is as small as possible. Rearwardly curved rotor blades and rotor ducts are therefore to be preferred to those forwardly curved, on the grounds just mentioned.

In order to ensure the fettering of the guide wheel, a single weight 20 would of course sufiice, whilst the second weight 20 would not be required. The second weight 20, bearing upon the inner diameter of the chamber 17, has however a further purpose to serve. If owing to any unforeseen circumstances, the external torque acting upon the guide wheel becomes greater than the opposing torque which the weights 20 can bring into action by the action of gravity, the guide wheel will be compelled to participate in the rotation. With only a single weight 20 present, the revolving guide wheel would then be considerably out of balance, and this might lead to the total destruction of the compressor.

The second weight 20 therefore serves to guard against this risk. As soon as the guide wheel participates in the rotation, the second weight 20 is immediately thrown outwards by centrifugal force, and takes up a position diametrically opposite to the first weight 20 on the outer periphery of the chamber 17, whereby any dangerous lack of balance is obviated. Cases in which the external torque acting on the guide wheel becomes so great that the guide wheel participates in the rotation may occur for instance if a bearing of the shaft 18 jams, owing to soiling or on other grounds, so that the free rotatability of the guide wheel is no longer provided. In such and other abnormal cases of operation, the second weight 20 affords protection against disturbance or destruction resulting from unbalance of the guide wheel, and this safeguard should not be omitted.

In the drawings, the first stage of the compressor bears the references 11 to 20. The second stage bears the corresponding numerals 21 to 30, and the third, the numerals 31 to 40. The three stages are all alike, except for the rotor ducts 13, 23 and 33, which are narrower in the second and third compressor stages than in the first, to correspond to the smaller volumetric capacity. A separate description of the second and third compressor stages is therefore unnecessary, apart from the indication that the shaft 38 of the third stage is journalled at the right-hand end in the casing cover 5.

The parts 12, 22 and 32 of the casing, and the casing covers 1 and 5, are bolted together or held fast to one another in a gastight manner in some other way, and form the external casing of the compressor, which according to the invention revolves with the rotors, which are connected fast with it in a gastight manner.

The air to be delivered and compressed enters the first compressor stage through intake apertures 41 in the casing cover 1, and flows through the three stages of the compressor in the same manner as in radial-flow compressors of known construction, the objectionable reverse fiow of delivered air through gaps being however obivated. After the air has passed through the third stage of the compressor, it is guided, by means of deflecting and reversing blades 35, to discharge apertures 42 in the casing cover 5, from which it finally passes into the hollow stub shaft or shaft end 43 of the casing cover 5.

To enable the compressed air thus delivered to be made available to the consumer, it must be transferred from the hollow revolving shaft end 43 into a stationary connecting pipe with connection possibilities for pipe lines. This measure requires a gastight stufiing-box or shaft packing between the shaft end 43 and a stationary connecting pipe.

In the constructional example illustrated in FIGURE 1 of the drawings, an axially acting shaft packing is provided, which is built up in the following manner: To the bearing block 7 is flanged a cup-shaped sealing casing 44, in which a sleeve 45 is so arranged as to be longitudinally slidable but secured against rotating. A packing ring 46, between the end face, machined clean and preferably also lobed, of the hollow shaft end 43 and the sleeve 45, may consist of carbon or of some other smooth and wear-proof packing material, and is preferably connected fast with the sleeve 45, for instance by means of an adhesive. The pressing of the sleeve 45, with the packing ring 46, on to the end face of the hollow shaft end 43, is provided for by a prestressed spring 47, which bears, by way of spring plates 48 and 49, both against the packing casing 44 and against the sleeve 45, and presses the latter, with the packing ring 46, against the hollow shaft end 43. For precluding leakage between the sleeve 45 and its guide in the packing casing 44 there may advantageously be employed an O ring 50 of rubber, located in an annular groove in the packing casing 44.

The right-hand plane surface of the packing casing 44 may be used for fianging on the consumers pipe lines.

In conclusion it may also be mentioned that the driving motor for the compressor may also be accommodated upon the mounting stand 8.

The gas delivered from the coinpressor can be withdrawn through a comparatively narrow cros section, in the constructional example through the hollow shaft end 43 of the casing cover 5, without having to put up with inadmissibly high gas speeds, if use is made of one advantageous property of the compressor according to the invention by keeping the delivery output low by not completely equipping the rotors with blades or rotor ducts.

The compressor according to the invention can obviously also be advantageously employed for large and even very large delivery outputs, the rotors being equipped with blades over the entire periphery in a known manner. The admission and discharge cross sections of the compressor will then be made correspondingly larger. Instead of the slip-ring packing 46 employed in the embodiment shown in the drawing, labyrinth packing of known construction may then be adopted.

In order to be successful, independently of the nature of the gas to be delivered and compressed, with a single shaft packing, the compressor of FIG. 1 is shown in FIG. 4 with its driving motor 51 to be lodged in a gastight housing 52 sealed to the mounting stand 8, the bearing block 7, and the frame which jointly constitute a gastight bottom cover for the housing 52. An escape of gas into the surrounding atmosphere even with small and not always avoidable leakages of the shaft packing, is thereby rendered impossible. This is of special importance in closed gas circuits, for instance refrigerating circuits, which must be absolutely fluidtight. The suction connection 53 on the stationary gastight housing 52 may be made absolutely gasproof. In the interior of the stationary outer housing 52, the gas-discharge end of the compressor that is sealed with a shaft packing is connected in a gastight manner with the associated outwardly leading connection at the sealing casing 44.

The structure, shown by way of example, of the compressor illustrated in the drawing, is not the only one possible. For instance it is also possible to shrink, on to a common continuous shaft, in a gastight manner, those parts of the casing that are connected fast and in a gastight manner with the rotors and are to be connected in a gastight manner with one another, and to journal the guide wheels in a readily rotatable manner thereon between the individual rotors. For the admission and discharge of the gas to be conveyed the shaft may be made hollow, and shaft packings similar to that shown in the constructional example may be employed.

The teaching of the invention could obviously also be adopted for single-stage turbo-compressors. The advantages of the compressor claimed as new, over turbo-compressors hitherto known, progressively increase as the number of stages becomes greater, because only one shaft packing is used regardless of the number of stages. Existing compressors need two shaft packings for each individual stage. On grounds of wear, these shaft packings must not be slip-ring packings but must be labyrinth packings, which do indeed reduce the harmful return flow of the gas through the gaps between rotors and casing to the gas-admission side of the rotors, but cannot fundamentally prevent it, as has already been explained above.

I claim:

1. A compressor comprising, in combination:

(a) a stationary support;

(1')) a casing mounted on said support for rotation about an axis, said casing defining an axial cavity therein and being formed with discharge means adjacent said axis;

(c) a rotor member fixedly mounted in said casing and sealingly engaging the same, said rotor member dividing said cavity into two portions, and defining a radially extending conduit having an orifice adjacent said axis in one of said portions, and another orifice remote from said axis in the other portion of said cavity, whereby a fluid may be centrifugally conveyed from'said one portion to said other portion when said casing rotates;

(d) guide Wheel means for deflecting conveyed fluid from the orifice of said conduit in said otherportion toward said axis and said discharge means, said guide Wheel means being rotatably mounted in said other portion of said cavity;

(e) drive means for rotating said casing about said axis; and

(f) fettering means for urging said guide wheel means toward a predetermined angular position relative to said support when said casing is rotated by said drive means.

2. A compressor as set forth in claim 1, wherein said fettering means include a weight eccentrically arranged on said guide Wheel means, said guide wheel means being mounted in said casing for rotation about a horizontally extending axis of rotation.

3. A compressor as set forth in claim 2, wherein said axis of rotation of said guide wheel means coincides with the axis of rotation of said casing.

4. A compressor as set forth in claim 1, wherein said guide wheel means is mounted on said casing for rotation about said axis, the axis extending horizontally, and said fettering means include two weights mounted on said guide wheel means on opposite sides of said axis for radial movement relative to said axis responsive to gravity.

5. A compressor as set forth in claim 1, wherein said rotor member is formed with a plurality of ducts having respective first orifices adjacent said axis in said one portion of said cavity, and respective second orifices remote from said axis in said other portion of said cavity, one of said ducts constituting said conduit, said second orifices being circumferentially spaced, and jointly extending over a minor portion of the circumference of said rotor member in said other portion, the remainder of said rotor member in said other portion of said cavity being impervious to the flow of fluid.

6. A compressor comprising, in combination:

(a) a stationary support;

(b) a casing mounted on said support for rotation about an axis, said casing defining an axial cavity therein;

(0) intake means and discharge means communicating with said cavity and axially spaced from each other;

(01) a plurality of rotor members fixedly mounted in said casing in axially spaced relationship axially intermediate said intake means and said discharge means, said rotor members sealingly engaging said casing and dividing said cavity into a plurality of axial portions, each rotor member defining a radially extending conduit having an orifice adjacent said axis in one of said portions, and another orifice remote from said axis in another portion of said cavity axially spaced from said one portion toward said discharge means, whereby a fluid may be centrifugally conveyed from said intake means to said discharge means when said casing rotates;

(e) guide wheel means in each of said portions for deflecting conveyed fluid from respective orifices of said conduits remote from said axis in a radially inward direction, said guide wheel means being mounted in the respective portions of said cavity for rotation about said axis;

(1) drive means for rotating said casing about said axis; and

(g) fettering means for urging each of said guide wheel means toward a predetermined angular position relative to said support when said casing is rotated by said drive means.

7. A compressor as set forth in claim 6, wherein said casing includes a plurality of substantially identical casing members, each casing member being fixedly fastened to a respective one of said rotor members, and being sealingly secured to an axially juxtaposed other casing member.

8. A compressor as set forth in claim 6, wherein one of said intake means and said discharge means includes a hollow shaft member mounted on said support, said casing being secured to said shaft member.

9. A compressor as set forth in claim 6, further com prising a stationary housing on said support and enclosing said casing anda portion of said support, one of said intake means and said discharge means opening into the interior of said housing, and connection means on said housing for connecting said interior to a conduit outside said housing.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A COMPRESSOR COMPRISING, IN COMBINATION: (A) A STATIONARY SUPPORT; (B) A CASING MOUNTED ON SAID SUPPORT FOR ROTATION ABOUT AN AXIS, SAID CASING DEFINING AN AXIAL CAVITY THEREIN AND BEING FORMED WITH DISCHARGE MEANS ADJACENT SAID AXIS; (C) A ROTOR MEMBER FIXEDLY MOUNTED IN SAID CASING AND SEALINGING THE SAME, SAID ROTOR MEMBER DIVIDING SAID CAVITY INTO TWO PORTIONS, AND DEFINING A RADIALLY EXTENDING CONDUIT HAVING AN ORIFICE ADJACENT SAID AXIS IN ONE OF SAID PORTIONS, AND ANOTHER ORIFICE REMOTE FROM SAID AXIS IN THE OTHER PORTION OF SAID CAVITY, WHEREBY A FLUID MAY BE CENTRIFUGALLY CONVEYED FROM SAID ONE PORTION TO SAID OTHER PORTION WHEN SAID CASING ROTATES; (D) GUIDE WHEEL MEANS FOR DEFLECTING CONVEYED FLUID FROM THE ORIFICE OF SAID CONDUIT IN SAID OTHER PORTION TOWARD SAID AXIS AND SAID DISCHARGE MEANS, SAID GUIDE WHEEL MEANS BEING ROTATABLY MOUNTED IN SAID OTHER PORTION OF SAID CAVITY; (E) DRIVE MEANS FOR ROTATING SAID CASING ABOUT SAID AXIS; AND (F) FETTERING MEANS FOR URGING SAID GUIDE WHEEL MEANS TOWARD A PREDETERMINED ANGULAR POSITION RELATIVE TO SAID SUPPORT WHEN SAID CASING IS ROTATED BY SAID DRIVE MEANS. 